Research is conducted to characterize and develop new animal models of human disease and to develop the means to better characterize a model's relevance, addressing critical barriers to research progress. Additional aims include the development of new research technologies for the evaluation and application of disease biomarkers. Progress was made in developing cancer diagnostics and in research resources useful in developing and characterizing new models of human cancer. This research project included developing capabilities in molecular diagnostics for cancer models, developing methods for automated morphometric image analysis of cancer specimens for quantitative pathology, and preclinical development of targeted therapy for mucosal melanoma. Unique spatial-spectral image analysis algorithms were developed for applying automated pattern recognition morphometric image analysis to quantify histologic tumor and non-tumor areas in biospecimen tissue sections. Development and application included algorithms to compute the degree of differentiation in experimental tumors mechanistically differentiated by altering various oncogenic signals under transcription factor control. Analysis of osteosarcoma was accomplished using this computer assisted diagnostic. Progress in computer assisted diagnosis also included clinical validation of primary diagnosis by computer display. Twelve pathologists participated in a multicenter clinical diagnostic review to assess performance agreement comparing conventional microscopy (CM) of glass slides with digital display of whole slide images (WSI) for the visual assessment and enumeration of tumor mitotic figures (MF). Several comparisons of agreement in identifying and quantifying MF among reads were made: 1) between-reader, within-modality 2), between-reader, between-modality, and 3) within-reader, between-modality. Agreement across conventional and digital microscopy modalities was evaluated using various means of data analyses in an attempt to determine if one or more modalities might be clearly superior for this task. Investigation aimed at assessing the functional interchangeablity across the three modalities is ongoing. New model development is taking place for melanoma treatment. Melanoma represents a significant malignancy in humans and dogs. Distinct from genetically engineered models, sporadic naturally occurring canine melanocytic neoplasms share several characteristics with human disease that could make investigation in dogs a more relevant pre-clinical model. Canine melanomas rarely arise in sun-exposed site and most occur spontaneously in the oral cavity. The spectrum of naturally occurring canine melanocytic neoplasia, as is true in people, includes benign lesions with some analogy to nevi, as well as invasive primary melanoma, and widespread metastasis. As in humans, distinct melanoma subtypes differing in somatic and predisposing germ-line genetic alterations, cell of origin, epidemiology, relationship to ultraviolet radiation and progression from benign to malignant tumors, may also exist in pet dogs. Both canine and human mucosal melanomas (MM) appear to harbor BRAF, NRAS and c-kit mutations uncommonly, compared to human cutaneous melanomas, although both species share AKT and MAPK signaling activation. We conclude that there is significant overlap in the clinical and histopathological features of naturally occurring canine and human MM. Naturally occurring canine oral cavity melanoma is being explored further as a pre-clinical model for human melanoma. The majority of human and canine MM evaluated exhibited RAS/ERK and/or PI3K/mTOR signaling pathway activation. Canine MM cell lines, with varying ERK and AKT/mTOR activation levels reflective of naturally occurring differences in dogs, were sensitive to MEK inhibition and dual PI3K/mTOR inhibition. Two-drug combination synergistically decreased cell survival in association with caspase 3/7 activation, as well as altered expression of cell cycle regulatory proteins and Bcl-2 family proteins. In combination, the two drugs targeted their respective signaling pathways, potentiating reduction of pathway mediators p-ERK, pAKT, p-S6, and 4EBP1 in vitro, and in association with significantly inhibited solid tumor growth in MM xenografts in mice. These findings provide evidence of synergistic therapeutic efficacy when multiple mediators are simultaneously targeted in melanoma with Ras/ERK and PI3K/mTOR pathway activation. An analogous interdisciplinary approach to comparing the suitability of naturally occurring canine brain tumors to inform human brain cancer research was organized with the CCR Comparative Oncology Program and extramural investigators. Conduct of a multi-center clinical diagnostic study in collaboration with the US Food and Drug Administration is leading to useful criteria for validation of whole slide digital pathology tissue image platforms for clinical cancer diagnosis.